Heat the oil over medium heat. Add the onion and saute for 5 minutes. Add the Rotel tomatoes and jalapenos. Cook another 2 minutes. Reduce the heat to low and add the cheese with 1/4 cup of the milk. Stir until melted. Add more milk as needed to get sauce to the right consistency. Note: The cheese dip will thicken quickly as it cools, so start off a bit thinner. Turn off the heat and stir in the cilantro. Serve immediately with tortilla chips and flour tortillas. This can be reheated in the microwave as needed. Enjoy!